The present invention is directed to a method for manufacturing an optical ribbon conductor or stripline, wherein a plurality of pre-coated light waveguides are conducted side-by-side through a coating arrangement that surrounds them and applies a coating material which serves the purpose of enclosing the light waveguides into a ribbon.
U.S. Pat. No. 4,147,407, whose disclosure is incorporated herein by reference thereto, discloses a method for manufacturing a ribbon conductor wherein pre-coated light waveguides, which are light waveguides that have been provided with a coating, are drawn through a rectangular nozzle as a solvent is additionally supplied to the nozzle. This solvent will cause softening of the coatings of the light waveguide so that the various coatings of the light waveguides will fuse to one another. Since the light waveguides must immediately touch each other in order to achieve the desired fusing, the opening can be selected only of such a size that the light waveguides will just fit therethrough. This, however, is not free of problems in view of the fact that the diameters of the coatings are subject to certain fluctuations. In addition, it is always required in this method that the coated light waveguides come into contact with the outside walls of the rectangular coating nozzle, and this contact will lead to an abrasion and/or to mechanical stressing of the light waveguides.
German Published Application 37 33 124 discloses a method for gluing light waveguides to one another in order to form an optical ribbon conductor or stripline, wherein the light waveguides are conducted through a rectangular coating nozzle. Here, too, it is provided that the individual light waveguides are pressed against one another, to which end a sliding contact under a spring bias is provided at one side of the coating nozzle. This sliding contact, in fact, enables a certain compensation of tolerances given diameter fluctuations of the coatings of each of the waveguides; however, the problem remains that the frictional forces and the undesirable and disturbing abrasion of the coating material can occur due to the close contact between the inside wall of the nozzle and the coating of each of the waveguides.
European Published Application 0 438 668 A2 discloses a coating method, wherein the light waveguides are conducted over at least one roller provided with grooves before entry into the coating means in order to impress a defined position and defined spacing relative to one another on the waveguides. However, it is not guaranteed without further ado that the light waveguides in fact retain the position which is imposed on them by the roller provided with grooves during the further travel through the coating means. A guide block is, therefore, additionally provided between the admission channel and the discharge channel, and this guide block comprises a plurality of grooves proceeding parallel to one another so that one light waveguide will lie in each of the grooves and the light waveguides are, thus, defined additionally and anew in terms of their spacing relative to one another.
All of the methods mentioned above proceed on the basis of the idea that the light waveguides must be aligned in terms of their position relative to one another by a mechanical guidance, whether it is the wall of the nozzle or by grooved guide rollers or guide blocks. This alignment will result in the fact that the light waveguides are always in contact with a mechanically rigid component part, namely the coating nozzle or the grooved guide means, or are touching these elements. Thus, stressing of the light waveguides due to friction and abrasion will occur and, moreover, difficulties can occur when the thickness of a pre-coating of the light waveguides has a higher tolerance value. Due to the mechanical stressing of the light waveguide coatings, moreover, the known methods have the disadvantage that high throughput speeds cannot be easily obtained because an increase in the throughput speed will cause a disproportionate increase in the mechanical stressing, particularly in view of the abrasion to be anticipated. An over-pressure of the coating material in the coating means, which pressure is applied in all methods, moreover, will cause a decentering or misalignment; for example, the fibers in the finished ribbon will not lie in one plane.